Rohff, 36, is accused of "premeditated" assault on the victim at a store that sells clothing under his arch-rival Booba's Unkut brand.
The 19-year-old sales assistant was left in a coma and fighting for his life after suffering a serious head injury when he was set upon by a gang of men in the central Paris clothing store.
Rohff, one of France's best-known rappers with album sales of 1.4 million, is embroiled in a long-running row with Booba, 37.
This image, tweeted out by France's I-Tele TV channel shows Rohff being taken away to Fresnes prison where he will remain in custody.
The two artists have for months been trading barbs in their songs and on social media, but the feud turned physical on Monday evening, when the artist went into the store and a fight broke out with the shop assistant.
Investigators were only able to question the victim on Tuesday after he emerged from a coma.
Rohff, whose real name is Housni Mkouboi, went voluntarily to a police station for questioning early Tuesday.
His lawyer Francis Terquem told AFP his client had admitted that he "delivered some blows" to the shop assistant. Legal sources said security camera footage showed Rohff hitting the victim, but that the rapper had denied the assault was premeditated.